Multiple Windows On Different Locations

I need to open multiple windows via javacript. The for-loop is willing to do that for me:

function open_multiple(){
for(i=1; i<=10; i++){
window.open(&#392;.htm', 'myWindow'+i)
}

There's no problem in using the var i in the naming of the windows.
What I'm struggling with is the var i in the positioning:

function open_multiple(){

for(i=1; i<=10; i++){
var x=30*i;
var y=30*i;
window.open(&#392;.htm', 'myWindow'+i, 'top='y', left='x);
}
}
As you can see, I've put the vars outside the string as part of the solution I allready found out. Obviously, as I'm still posting this; it doesn't work yet. :o I must be overlooking something.

if (anyone can point out my mistake here){
document.write("thanks a million")
}